1. Field of the Invention
This invention relates to an olefin polymerization or copolymerization method by means of a novel polymerization catalyst. More particularly, it is concerned with a method for the preparation of polyolefins which comprises polymerizing or copolymerizing an olefin or olefins in the presence of a novel catalyst produced by supporting on a reaction product obtained by reacting (1) an aluminum compound represented by the general formula Al(OOCR)(OR').sub.2 wherein R and R' being the same or different each represent alkyl, aryl or aralkyl and (2) a magnesium compound represented by the general formula Mg(OR").sub.2 wherein R' being the same as or different from R and/or R' is alkyl, aryl or aralkyl at a molar ratio of (1):(2) of substantially at least 2:1 a titanium compound and/or a vanadium compound and subsequently activating the same with an organometallic compound or compounds.
2. Description of the Prior Art
It is well known in the prior art that combined systems of a titanium or vanadium compound and an organometallic compound of metals of Groups I - III in the Periodic Table are good catalysts for the olefin polymerization. However, these systems leave something to be improved in their polymerization activities being still low compared with the desired high one in the preparation of polyolefins. On the other hand, it is also known that catalyst systems composed of a titanium or vanadium compound, a component of Ziegler catalyst supported on a carrier of various magnesium compounds such as magnesium oxide, hydroxide and chloride are another class of good catalysts for the olefin polymerization. In this respect, a number of studies have recently been made of the use of a variety of metal compounds including magnesium ones as the carrier.